**Are demons strong as angels?**

That will depend on the particular demon!

Some demons may be more superiorly stronger than some angels but not all.  The fallen angels also called demons did not lose their nature or their connatural gifts at the moment of the turn away from God. Thus a demon from the order of Cherubims  will be superior in strength than Angel from the order Dominions. 

Since demons have not lost their con natural powers when  they fell, one can not say with certitude which demon is stonger than which Angel. The differences between the angels is far greater than the differences between men and the various races of mankind. Each Angel being uniquely created by the Almighty, makes each Angel unique and endowed with it’s own individual powers. We have no way to determine which Angel is stronger than which demon and vice versa, except between the various choirs of angels.

Although it is now generally accepted that there are [nine choirs of angels][1] and each choir is of angel is different and ranked accordingly.

> During the Middle Ages, many schemes were proposed, some drawing on and expanding on Pseudo-Dionysius, others suggesting completely different classifications. According to medieval Christian theologians, the angels are organized into several orders, or "Angelic Choirs”.
> 
> Pseudo-Dionysius (On the Celestial Hierarchy) and Thomas Aquinas (Summa Theologica) drew on passages from the New Testament, specifically Ephesians 1:21 and Colossians 1:16, to develop a schema of three Hierarchies, Spheres or Triads of angels, with each Hierarchy containing three Orders or Choirs. Although both authors drew on the New Testament, the Biblical canon is relatively silent on the subject, and these hierarchies are considered less definitive than biblical material.
> 
> Choirs in medieval theology
> 
> St. Thomas Aquinas in Summa Theologica (1225–1274):
> 
> 1. Seraphim, Cherubim, and Thrones;
> 
> 1. Dominations, Virtues, and Powers;
> 
> 1. Principalities, Archangels, and Angels. 
> 
> [Christian angelology (Wikipedia)][1]

St. Thomas Aquinas' list is by far the most widely accepted list of angelic choirs and places the Seraphic order of angel as being at the highest level of angels followed by the Cherubim, and so on. According to St Thomas:

> 1. **The angels that rebelled and became demons did not lose their nature or their connatural gifts**. They cast away, by their sin, the grace in which they were created. They did not cast away the beatific vision, for they never had it. Now, if we think of angelic orders as orders of angels in glory, then, of course, there are no orders of bad angels. But if we consider angelic orders as order of angelic nature simply, there are orders among the demons.
> 
> 2. Certainly, there is a precedence among bad angels; there is a subjection of some to others.
> 
> 1. Demons of superior nature do not enlighten inferior demons; enlightenment here could only mean the manifestation of truth with reference to God, and the fallen angels have perversely and permanently turned away from God. But demons can speak to one another, that is, they can make known their thoughts to one another, that is, they can make known their thoughts to one another, for this ability belongs to the angelic nature which the demons retain.
> 
> 1. The nearer creatures are to God the greater is their rule over other creatures. Therefore, the good angels rule and control the demons. - [Orders Among the Fallen Angels][2]

This stated it only makes sense that Satan was a Seraphim, for surely some of the Seraphim fell in great revolt against God. **Although one can not say with certainty it is generally believed Satan was a Seraphim.**

The thing that tips the balance in favour of the Good Angels is not only the fact that they were superior in number, but also that they **cooperated** with God’s grace. St. Paul’s words I never [Romans 5:20][3] are very telling here:

> Now the law entered in, that sin might abound. And where sin abounded, grace did more abound.

And again: 

> What shall we then say to these things? If God be for us, who is against us? [Romans 8:31][4]

  [1]: https://en.m.wikipedia.org/wiki/Christian_angelology
  [2]: https://www.jesus-passion.com/angels.htm
  [3]: https://www.biblegateway.com/verse/EN/Romans+5:20
  [4]: https://www.biblegateway.com/verse/en/Romans%208%3A31